Microsoft has made Windows 8's final release available to MSDN and TechNet subscribers, so if you are one of those - have fun. The 90-day trial has also been released, so us mere mortals can have a go at it as well. The evaluation version is Windows 8 Enterprise, so it contains a number of features regular users normally won't see. As far as I can tell - it's a bit unclear - the trial version cannot be upgraded to a final version a few months down the line. Happy testing!